EFFECTS OF DIFFERENT STORAGE MATERIALS AND INFESTATION BY CALLOSOBRUCHUS MACULATUS ON THE SHELF LIFE OF COWPEA AND SOYBEAN SEEDS.

Abstract

The effects of different storage materials and infestation by Callosobruchus maculatus on the shelf life of cowpea and soybean (IT 89-288, IT 96-610 for cowpea and TGX 1448, TGX 1987 for soybean) seeds were investigated in this study. The storage materials used were plastic containers and nylon bags of 1250μ and 60μ thickness respectively. Callosobruchus maculatus were introduced into one batch of the storage materials. The objectives of this study were to establish the effects of levels of infestation, different storage materials and storage duration on the functional, proximate, pasting, rheological properties and percent weight loss of the cowpea and soybean seeds stored. The cowpea and soybean seeds were disinfested prior to use by freezing technique. The initial weight, temperature, relative humidity, functional, pasting, proximate, rheological properties and percent weight loss were determined and these were repeated at interval of four weeks for a period of three months. Higher mean values of ash, fat and protein: 4.75, 16.83 and 32.57% respectively were recorded in seeds stored in nylon and lower value of moisture (10.65%) compared to 11.23% in plastic. Plastic and nylon storage materials used had no significant effect on the functional properties determined except for bulk density in which 0.78g/ml and 0.83g/ml were recorded in nylon and plastic materials respectively. Higher mean values of water, oil, foaming, least gelation and swelling capacities were however obtained in the seeds stored in nylon. Higher mean values of rheological properties were obtained in the seeds stored in nylon except for yield point, density and temperature. There were no significant differences (p ≤ 0.05) in the pasting properties determined except for peak time and percent weight loss of cowpea and soybean seeds stored in nylon and plastic, though more moisture were lost in the nylon than in the plastic. It can therefore be concluded that, the 60μ nylon a better storage medium for the seeds as it permits exchange of gases and some transmission of moisture from the package to the atmosphere. This to some extent had prevented recondensation of moisture on the seeds which could be responsible for the increase in moisture of seeds stored in plastics than those stored in the nylon as storage progressed.